Apparatus for improving the surface



March 10, 1964 R. P. MAHONEY 3,124,481

APPARATUS FOR IMPROVING THE SURFACE CHARACTERISTICS OF A PAPER WEB Filed Sept. 19, 1960 IN V EN TOR. I41! 2 fi/lbU/Vf) 1% w Z H 2,

A TTORNE YS United States Patent 1 3,124,481 APPARATUS FOR IMPROVING THE SURFACE CHARACTERKSTICS OF A PAPER WEB Ralph P. Mahoney, Beioit, Wis, assignor, by mesne assignments, to Beloit Corporation, Beloit, Wis, a corporation of Wisconsin Fiied Sept. 19, 1960, Ser. No. 56,719 Claims. Cl. 11860) The present invention relates broadly to the production of paper and related web materials and is more particularly concerned with improved methods and means for sized or wetted paper materials surface finishing.

Machine glazed paper has heretofore been produced by employment of a pressure roll which applies the paper against the surface of a conventional Yankee dryer. Pressing of the paper against the Yankee dryer drum compacts the paper web on the dryer, and, the side of the paper sheet contacting the polished dryer surface is provided with a fine-glazed shiny surface by drying of the sheet in this manner. This process requires that the drying take place in contact with the dryer surface and, therefore, production speed is limited by the diameter of the drying drum and steam pressure of the process. It is well known that if the sheet is removed from the dryer drum before a certain moisture content is removed from the sheet, the surface finish of the side of the paper sheet in contact with the dryer drum will be ruined.

By employment of the present invention I provide improved methods and means for the production of paper having surface finishes comparable to the surface of machine glazed paper.

It is, therefore, an object of the present invention to provide improved finishes for paper and related Web materials.

It is another object of the present invention to provide an improved method for finishing sized and/or wetted paper web materials.

It is still another object of the present invention to provide improved smooth, glazed and sealed surfaces on paper and related web materials.

Yet another object of the present invention is to provide an improved paper and paper board product having fine glazed surfaces on either one or both sides thereof.

It is still another object of the present invention to provide improved methods and means for finishing paper, paper board and like sheet and web materials which are simple and compact in construction and efficient and high speed in operation.

These and other objects, features and advantages of the present invention will become apparent upon a careful consideration of the following detailed description, when considered in conjunction with the accompanying drawing illustrating preferred embodiments of the concepts of my invention, wherein like reference characters and numerals refer to like and corresponding parts throughout the several views.

On the drawing:

FIGURE 1 is a partially diagrammatic view in side elevation of apparatus found useful in the practice of the present invention for finishing one side of a paper web.

FIGURE 2 is a fragmentary view in side elevation illustrating the finishing nip concept of the present invention and shown on an enlarged scale.

FIGURE 3 is a partially diagrammatic view in side elevation illustrating apparatus for finishing both sides of a paper product in accordance with my invention.

As shown on the drawing:

Briefly stated, the present invention involves the production of smooth, glazed and sealed surfaces on paper and related web materials wherein the surface to be finished is first wetted with a liquid, the wetted surface is then immediately brought in contact with a solid, precisely finished finishing surface heated to a temperature substantially above the boiling point of the liquid, the paper material is then briefly and firmly pressed against the solid surface and is removed thereafter from contact with the solid surface simultaneously with the release of the pressure thereagainst.

As appears in FIGURE 1, apparatus constructed in accordance with the principles of the present invention may be employed for finishing one side of paper, paper board and related web materials.

The surface of the paper web to be finished is first wetted with water or with a sizing solution in any conventional manner, such as by spray means, shower means, immersion tank, roll coating arrangement. For purposes of the present example, the surface S of the web W to be finished is brought in contact with the roll 5 of a roll coating arrangement, generally indicated by the numeral 6, for the application of water or a conventional size thereto.

Preferably the surface of the paper material is smoothed and leveled to smooth any excess Water or size. For this purpose, an air doctor 6a may be employed. A suitable air doctor is disclosed in US. Patent No. 2,139,- 628, issued to Terry.

The web W with its surface in the wetted or wet size condition is immediately brought in contact with a highly polished finishing roll 7 for the finishing treatment. It is generally desirable when starches are used as size material to provide for some drying prior to entering the nip N, thereby avoiding sticking to the surface 8.

In the arrangement shown in FIGURE 1, the finishing apparatus may take the form of a driven roll 7 having a highly polished finishing surface 8 and a pair of hard surfaced but resilient backing rolls 9 and 10. Backing rolls 9 and 10 may be driven by contact with the Web W and finishing roll 7, or drive means (not shown) may be provided.

The finishing roll 7 may be constructed to provide the surface temperature required to dry the web in the finishing nip N. For this purpose, a suitable source of heat medium may be introduced into the internal chamber defined by the finishing roll 7 through a conduit 11. The metal finishing roll 7 having a highly polished surface 8 defines a narrow nip N with the resiliently surfaced pressure backing roll 9 which is of high surface hardness. The surface of the finishing roll 7 may be plated, as with chrome or nickel, and the resilient rolls 9 and 10 may comprise a metal core having a rubber cover of the desired hardness.

I have also found that the web may be immediately removed from the finishing nip without damaging the finish and other desirable characteristics of the web and without the requirement for permitting extended contact between the web and finishing roll. This characteristic is directly opposed to the characteristics of machine glazing of paper on Yankee dryers.

To minimize the operating pressure loading of the respective finishing and backing rolls, it is desirable that the resilient rolls 9 and 10 be quite hard, i.e., less than 30 P. and J. /8" ball). Employment of the hard surface rolls permits concentration of the total uniform pressure loading on a relatively narrow nip, in the direction of travel of the Web, and, excellent results have been obtained when the nip N is of a cross-sectional width, less than 1" and preferably about /2". The development of high unit pressures in a narrow nip N is desirable only below the crushing point of the web fibers. The hard and narrow nip assures uniform loading across the entire width of the sheet. it will be appreciated, of course, that continued use of the nip will tend to cause the re silient or hard rubber surfaced rolls 9 and 10 to soften slightly due to the temperature conditions existing at the nip and due to the effects of working engagement with the web during operation. In order to maintain the backing rolls at the desired high hardness level and thereby the nip width within the desired limits, means may be employed, if desired, to cool the resilient rolls. As will be fully appreciated by those versed in the art this may be done in various ways and is shown schematically in FIG. 1 by coolant supply lines 29a and 300 leading to the rolls 9 and 10. For this purpose, a cooling agent may be maintained in the interior of each of the backing rolls.

The temperatures maintained at the nip in conjunction with the other nip conditions, must be sufiicient to dry and finish the surface of the Web in contact with the finishing roll and to permit the pressure applied by the backing roll to smooth, blend and finish the surface While it is in the nip. Generally, the temperature at the nip is maintained above the boiling point of water or size employed and no known upper temperature limit exists other than the vaporization or decomposition temperature of the particular water or sizing material involved.

Experience has indicated that the transversely and uniformly distributed high intensity unit pressure at the ni is preferably within the range of from about 250 lbs. per square inch to about 2400* lbs. per square inch, depending primarily upon the particular paper web material involved.

Thus, in the nip, the pressure and the high surface temperature of the finishing roll induce drying of the web surface and finishing thereof while at the same time the resilience of the hard surface backing roll permits sufficient yielding in the nip to minor web thickness inequalities whereby the bulk and opacity of the Web material is not materially reduced.

The above degree of resiliency avoids the disadvantage inherent in conventional calendering apparatuses and methods in which spot density of the web is increased thereby producing hard glossy spots which will not accept printing impressions. The unit pressures employed are significantly less than those employed in paper calendering machines and the speeds obtainable are much higher than those normally available for machine glaze and cast coating applications.

Satisfactory finishing results are obtained at any practical operating speeds and, therefore, finishing operating speeds are limited only by the operational speeds of the paper making machine itself or the web supply means and of the finishing and backing rolls. It will be appreciated that finishing temperatures are generally in direct relation to operating speeds. For example, satisfactory finishing of paper board in the above manner which was supplied at the rate of 500 ft. per minute was obtained with finishing roll and nip temperatures of approximately 300 F. and nip pressures of 400- lbs. per linear inch. Similarly, satisfactory finishing results were obtained with a light weight paper running at 2000 ft. per minute through a pressure nip of approximately /2 width maintained at a temperature of 345 F. and pressures of about 400' lbs. per linear inch.

As aforesaid, the finished surface of the web may be immediately removed from the nip and may be fed to a winding reel (not shown) or may be permitted to remain in contact within the finishing roll 7 preparatory to a second finishing treatment in the nip defined by the finishing roll and the hard surface backing roll 10, if desired.

To vary the pressure applied at the nip for finishing difierent weight paper and board, means therefore may take the form of a hydraulically or pneumatically operated piston assembly 12 having its piston rod 13 connected to a cross arm 14 of a pair of support members 15 which carry brackets '16 for mounting the shaft 17 of the backing roll 9. The support members 15 may be pivotally mounted to the support stanchion 18. Pneumatic or hydraulic operating pressures of the piston arrangement need only be increased or decreased in order to 4. produce a corresponding pressure on the finishing roll and web.

A similar piston arrangement may be employed for controlling application of finishing pressure by the resilient backing roll 10 which includes a piston housing (not shown) a piston rod 19 mounted on a cross arm of a pair of support members 20 mounting the bearing brackets 21 of roll 10. Support arms 20 may be fulcrumed to a clevis 22 which is mounted on the frame stanchion 23. Thus by employment of a pair of support members 20, transverse uniform pressure is applied at the nip.

After having been removed from the nip defined by the backing roll 9 and finishing roll 7, the web may be led around a pair of fiy rolls 24 and 25, as appears in FIG- URE 1, for subsequent introduction thereof into the nip defined by backing roll 10' and finishing roll 7. Employment of fly rolls 24 and 25 is made possible since the web is dry. If desired, the web may undergo a second finishing treatment in the nip defined by the pressure backing roll 10 and finishing roll 7. It will be appreciated that the pressure roll 10 is identical in construction and operation to pressure roll 9. After leaving the latter nip, the such may be then fed over a guide roll 26 to be wound on a reeler (not shown) awaiting subsequent disposition.

As appears in FIGURE 2 wherein the dried and finished web is shown in exaggerated form, the web, enters the narrow width and hard nip defined by rolls 7 and 9 with the wet surface thereof brought in contact with the finishing surface of roll 7 where, while in the nip, the surface is dried and glazed. -It *will be appreciated that the desired finishing results are accomplished where only one finishing nip is employed and that such apparatus may be utilized for on or off the paper making machine applications.

As appears in FIGURE 3, an alternate arrangement may be provided for on or off the machine finishing of both sides of the paper stock. In this arrangement, the web is fed over the water or size applicator roll 5 of the roll arrangement 6 for introduction thereof into the narrow width and hard finishing nip defined by the heated finishing roll 7 and backing roll 9. The web is introduced into the nip with the wetted or sized surface in contact with the finishing surface 8 of roll 7.

The operating conditions of temperature and pressure are similar to those heretofore described. The wetted and/ or sized web, while in the nip, is dried and a finished 0r glazed, comparable to the glaze obtained with employment of machined glazed paper rolls of the Yankee dryer arrangement, is obtained. The web may be removed immediately from the nip and, if desired, may be permitted to remain in contact with the finishing roll 7 to be introduced into a second glossing nip defined by finishing roll '7 and the second resilient backing roll 10.

Means are also provided for varying the pressure applied by rolis 9 and I0 and may take the form of a hydraulic or pneumatically operated bellows arrangement 28. The end cover 29 of the bellows arrangement may be connected to a movable link 30 which is pivotally connected at one end to the arm 31 fulcrumed to the bearing of the shaft 32 of roll 10. Arm 31 is connected at the other end to a bracket 33 mounted on the frame stanchion 34. Similarly, the end plate 35 of the bellows arrangement may be connected to a movable link 36 which is pivotally connected to a member 37 fulcrumed to the bearing shaft 38 of backing roll 9. Arm 37 is pivotally connected to a bracket 39 mounted on the machine frame member 34. Similar arm, link, and bracket assemblies, not shown, connect the bellows arrangement 28 to the opposite sides of rolls 9 and 10 to obtain equal distribution of pressure transversely across the hard narrow width nip N. Thus, as pressure in the bellows is increased, the bellows expand and backing rolls 9 and It will exert greater pressure against the finishing roll 7. Conversely, when pressure is decreased in the bellows, the bellows contract and less pressure is exerted by backing rolls 9 and on finishing roll 7. It will be appreciated, however, that any conventional means may be employed to vary pressure application by either one or a pair of back ing rolls, depending upon the finishing arrangement adopted.

After leaving the hard narrow width nip defined by rolls 7 and 9, the web surface is dry and glazed and may then be fed around a plurality of guide rolls 42 and 43 to a water or sized applicator roll 44 for Wetting or sizing of the untreated side of the web. Aft-er having been wetted or sized on the latter side, the web is then fed immediately into a hard, narrow width nip N defined by a highly polished finishing roll 7' and a resilient backing roll 9' having a surface of high hardness for finishing of this side of the paper web. An additional finishing treatment of .the second side of the web may be accomplished, if desired, in a similar nip N" defined by the finishing roll 7' and a backing roll 10'. Finishing roll 7' may be similar in construction and operation to finishing roll 7, and, similarly, backing rolls 9 and 10' may be similar in construction and operation to backing rolls 9 and 10 respectively. Means 45, similar in construction and operation to means 28, may be employed to vary the pressure applied by backing rolls 9 and 10.

Thus when the web leaves the latter nip N, both sides of the web are dried to an atmospheric moisture content and provided with a glazed surface finish.

It will be appreciated that if the web is introduced into the nip N immediately after its second surface is wetted or sized and prior to penetration of the water or size completely through the web, the second surface of the web may be glazed without substantially affecting the finish of the first glazed side of the web and other desirable characteristics of the web.

The web with both surfaces finished may then traverse a plurality of guide rolls 81 and 82 and be taken off the machine on a reeler (not shown) for subsequent disposition. Satisfactory finishing results have been obtained from various wetted and sized paper webs and board with the finishing surfaces of the finishing rolls heated to a temperature within the range of from about 220 F. to about 400 F., while I prefer to employ temperatures within the range of from about 280 F. to about 360 F.

It will be appreciated also that employment of a pair of Yankee drums for finishing either a single or both sides of a wetted and/ or sized web is limited in speed rate by the diameter of the roll and the heat which may be employed. In addition, cast coating methods require controlled moisture contents of the web in order to produce a finish on one or both sides of a web. The present invention eliminates these factors to a large extent as critical design parameters for obtaining finishes on one or both sides of a paper web or board comparable to the machine glaze finish obtained by cast coating methods.

Thus by employment of my invention, I provide means for finishing paper web materials and related web materials having a variety of applications.

In general, the heat and pressure in the hard, narrow nip should be controlled to conform the surface being finished to the surface of the finishing roll without crushing the web and under conditions which accommodate removal of the web without disturbing the conformed web surface. Usually, tolerable moisture contents are lessened with increases in either nip temperature or nip pressure and enlarged with increases in basis web weight.

Although various minor modifications might be suggested by those versed in the art, it should be understood that I wish ot embody within the scope of the patent warranted hereon all such embodiments as reasonably and properly come within the scope of my contribution to the art.

I claim as my invention:

1. In an apparatus for improving the surface characteristics of a paper web, the combination comprising,

a first large diameter roll having a smooth precisely tfinished non-resilient surface,

a second roll formed of a metal core and an outer resilient cover having a high hardness being in nipdefining relationship with said first roll,

said second roll being smaller than said first roll and forming a narrow nip therebetween,

wetting means positioned ahead of the nip applying a liquid to the surface of the (web exposed to said first roll,

heating means heating the surface of the first roll to a temperature of between a lower limit of 220 F. and an upper limit up to the decomposition point of the paper web to pl-asticize the surface of the web in the nip,

and means forcing the rolls together forming a trans- Wersely uniformly distributed high intensity unit pressure in said nip of between 250 pounds per square inch to 2400 pounds per square inch,

so that the wetted surface of the Web is glossed in the nip.

2. In :an apparatus for improving the surface characteristics of a paper web, the combination comprising,

a first large diameter roll having a smooth precisely [finished non-resilient surface,

a second roll formed of -a metal core and an outer resilient cover having a high hardness being in nipdefining relationship with said first roll,

said second roll being smaller than said first roll and forming a narrow nip therebetween,

Wetting means positioned ahead of the nip applying a liquid to the surface of the web exposed to said first roll,

heating means for heating the surface of the first roll to plasticize the surface of the web in the nip,

means forcing the rolls together forming a transversely uniformly distributed high intensity unit pressure in said nip,

and guide means separating the web from the surface of the first roll substantially immediately following the nip,

so that the wetted surface of the web is glossed in the nip.

3. In an apparatus for improving the surface characteristics of a paper web, the combination comprising,

a first large diameter roll having a smooth precisely finished non-resilient surface,

a second roll formed of a metal core and an outer resilient cover having a high hardness being in nipdefining relationship with said first roll, I

said second roll being smaller than said first roll and forming a narrow nip therebetween,

wetting means positioned ahead of the nip applying a l-iqltliid to the surface of the web exposed to said first ro heating means for heating the surface of the first roll to plasticize the surface of the web in the nip,

means for cooling said second roll for maintaining the cover of said second roll at the desired high hard- HESS, I

and means forcing the rolls together forming a transversely uniformly distributed high intensity unit of pressure in said nip,

so that the wetted surface of the web is glossed in the nip.

4. In an apparatus for improving the surface characteristics of a paper web, the combination comprising,

a first large diameter roll having a smooth precisely finished non-resilient surface,

a second roll formed of a metal core and a relatively thin outer resilient cover of a plastic having a high hardness of less than 30 P. and J. ball) being in nip-defining relationship with said first roll,

' said second roll being smaller than said first roll and forming a narrow nip therebetween,

means spaced ahead of the nip applying a size to the surf-ace of the web exposed to said first roll,

heating means for heating the surface of the first roll to a temperature of between a lower limit of 220 F. and an upper limit up to the decomposition point of the web to plasticize the surface of the web in the p,

and means forcing the rolls together forming a transversely uniformly distributed high intensity unit of pressure in said nip of between 25 0 pounds per square inch to 2400 pounds per square inch,

so that the sized surface of the Web is glossed in the nip.

5. In an apparatus for improving the surface characteristics of a paper web, the combination comprising,

a first large diameter roll having a smooth precisely finished non-resilient surface,

a second roll formed of a metal core and an outer resilient cover having a high hardness being in nipdefining relationship with said first roll,

said second roll being smaller than said first roll and forming a narrow nip therebetween,

first wetting means spaced ahead of the nip between said rolls applying a liquid to the surface of the web exposed to the first roll,

heating means heating the surface of the first roll to a temperature of between a lower limit of 220 F. and an upper iimit up to the decomposition point of the paper web to plasticize the surface of the web in the nip,

a third large diameter roll having a smooth precisely finished non-resilient surface,

a fourth roll for-med of a metal core and an outer resilient cover having a high hardness being in nipdefining relationship with said third roll,

said fourth roll being smaller than said third roll and forming a narrow nip therebetween,

second wetting means spaced ahead of the nip between said third and fourth rolls applying a liquid to the surface of the web exposed to the third roll,

heating means heating the surface of said third roll to a temperature of between a lower limit of 220 F. and an upper limit up to the decomposition point of the paper web to pl-asticize the surface of the web in the nip,

'and means forcing said first and second rolls together and means forcing said third and fourth rolls together forming a transversely uniformly distributed high intensity unit pressure in each of said nips of between 250 pounds per square inch to 2400 pounds per square inch,

so that the wetted surfaces of said web will be glossed in the nips.

References Cited in the file of this patent UNITED STATES PATENTS 287,500 Boyne Oct. 30, 1883 629,937 Trot-man Aug. 1, 1899 2,291,616 Fletcher Aug. 4, 1942 2,312,310 Bradner et a1 Mar. 2, 1943 2,313,497 Adrian Mar. 9, 1943 2,746,878 Rush May 22, 1956 2,759,847 Frost et all Aug. 21, 1956 2,769,725 Hart Nov. 6, 1956 2,867,414 Maloney et al Jan. 6, 1959 2,950,989 Freeman Aug. 3 0, 1960 2,999,786 Downs eta] Sept. 12, 1961 2,999,787 Downs et a1 Sept. 12, 1961 OTHER REFERENCES Pulps and Paper Manufacture, vol. 3 (1953), McGraw-Hill (New York) (pp. 275 and 511 to 517 relied on). 

4. IN AN APPARATUS FOR IMPROVING THE SURFACE CHARACTERISTICS OF A PAPER WEB, THE COMBINATION COMPRISING, A FIRST LARGE DIAMETER ROLL HAVING A SMOOTH PRECISELY FINISHED NON-RESILIENT SURFACE, A SECOND ROLL FORMED OF A METAL CORE AND A RELATIVELY THIN OUTER RESILIENT COVER OF A PLASTIC HAVING A HIGH HARDNESS OF LESS THAN 30 P. AND J. (1/8" BALL) BEING IN NIP-DEFINING RELATIONSHIP WITH SAID FIRST ROLL, SAID SECOND ROLL BEING SMALLER THAN SAID FIRST ROLL AND FORMING A NARROW NIP THEREBETWEEN, MEANS SPACED AHEAD OF THE NIP APPLYING A SIZE TO THE SURFACE OF THE WEB EXPOSED TO SAID FIRST ROLL, 